


The Little Byleth

by Tora93



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - The Little Mermaid Fusion, Blue Lions are humans, Byleth's voice, Childhood Friends, Dimitri's Eyes, F/M, Fluff, Friends to Lovers, Mentions of survivor's guilt, No eyepatch for Dima, Romance, Sign Language, The church people and some students are mermaids, sothis is a guide for her
Language: English
Status: In-Progress
Published: 2020-04-23
Updated: 2020-05-21
Packaged: 2021-03-02 00:02:24
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 9,995
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23795827
Author URL: https://archiveofourown.org/users/Tora93/pseuds/Tora93
Summary: When a young girl named Byleth finds a boy named Dimitri for the first time, she learns everything she can from him but she has to keep a little secret from him. A Very fishy secret. Despite warnings about the human world, Byleth longs for a life outside of the sea and to spend her days amongst a world she knows isn't all that bad. However, when Dimitri is called away for school, Byleth spends her days learning about humans waiting for him to come back.Years later, when a storm hits his ship, Byleth meets him again for the first time, but only after rescuing him, yet she doesn't recognize him except for a familiar pair of eyes. After singing to him, Dimitri instantly falls in love with her and she does the same. Knowing she can't meet him again as a mermaid, she goes to the Seawitch but at a price her voice and Dimitri's childhood memories. Yet she still finds a way to communicate in hopes he will recognize her. But will she be able to do it before it's too late?(Little Mermaid AU But with a few twists)
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth
Comments: 6
Kudos: 30





	1. The Merchild and the Little Prince

On a bright and warm summer day at the beach, a young boy with eyes as blue and bright as sapphires and hair as gold as wheat sat on the shore with a book listening to the gentle waves of the clear sea splash on the rocks and sand under a cornflower sky. "Your highness, are you doing alright reading by the shore? You don't want to lose a fine piece of literature." Called out a voice. "I'll be fine I'm not even that close to the sea. And it's a beautiful day, it's perfect for reading. What could happen?"

Deep under the waves, the fish swam free in schools around the corals, seaweed, and shells. But even deeper than most fish lived a world of people no human has ever seen, the world of merpeople. Each merperson looked just the way it was written in fairytales, a human top, a fish bottom, scales that shined in the light all swimming and flowing with the ocean's gentle embrace. One little mermaid who was just a child had dark teal hair and a deep violet tail was seen by a brawny and scared merman collecting objects in her satchel. "Byleth, are you done yet? I need to get to our place soon. Queen Reha won't be happy if we're not home with that report." She sealed up her bag, "Yes father!" She beamed. The pair swam in the direction of a giant castle made from ivory corals that shined like a polished gemstone.

Inside they made their way to a courtroom decorated wall to wall with flawless shells, seaweed, pearls, gold flecks, and corals. On the throne regally sat a mermaid with long bright flowing jade hair, a pearl-white tail, a long golden and royal blue cape, and a gilded tiara.   
  
"Sir Jeralt, I am happy you've come home on time. Anything new to report from today's outing?" She inquired. "Not much your majesty, but I can assure everything was taken care of properly." She then caught a glimpse of the child, "And Byleth?" Byleth instantly opened her bag, "Just a few things I found in the sand while father was working." 

Inside of her bag were various pieces of silver tools, and gears with some parts that looked brand new. Rhea gasped at the sight. "Young child, those are human objects. You haven't been near the surface have you?" Byleth bit her lip, "No, I haven't I just found them in the sand. Father was with me when I did it." She turned to Jeralt, "The kid is telling the truth, your majesty. I was there and she just found them. There's no way she would go to the surface, we both know it's too dangerous, and so are humans.

Byleth answered back, "Father, they can't be that bad. They make good stuff." Jeralt's spine shook.  
  
Rhea argued, "Little one, every mermaid and merman has been told that humans are dangerous, some go to the surface, but they don't come back!" "But your majesty..." A well-built merman with neck length emerald hair and a chinstrap beard arrived and lectured, "Young child, her majesty is correct. Your mother is gone because of humans. It's one of the reasons I keep my younger sister Flayn close to me at all times. I've even seen humans take a mermaid who I knew very well. So heed this warning, Byleth."  
  
Byleth sighed, "Okay, I've never been to the surface, but I just like finding things I'll be in my room and then get rid of it"

As Byleth swam away she went well past the palace and into a dark deep area where not a single soul was around, she soon came to a stone that was twice the size of her body and gently moved it to reveal a hole the same size and went inside before quickly sealing the area. Once inside, Byleth was surrounded by stone levels that acted like shelves to the various tools she has collected. Nearly every shelf was lightly decorated with silver, metal, gears, and papers.  
  
"Another day, another set of objects to the collection. I wonder if the beach has some more stuff?" After emptying her bag, she swam up to the light peaking through the waves, and breached the water. "Ahh! It's so nice to feel the air." Blyeth quickly flipped her fins and went towards the white sandy shore and peaked her head up to see something that she would've only dreamed of, a human boy. She swiftly hid behind a set of rocks but it was too late, he caught sight of the young mermaid and put down his book as he walked towards her.  
  
"Hello, it's just me here today. I won't hurt you, whoever you are." Byleth's heart was racing a million miles a minute, a human just saw her and she wanted to dive away, but her thoughts said no, and she took a chance. After hiding her tail, she and the boy's eyes finally met. "Oh, I didn't think anyone else was here. I'm Dimitri, I'm the prince of this kingdom." He introduced himself, "What's your name? I haven't seen anyone like you around here before." Byleth gently breathed, "I'm Byleth, and I'm not really from your land. You could say I'm from underneath to a degree and I also enjoy swimming a lot, your highness." Dimitri insisted, "No need to be formal, we're just kids." He then guessed, "So you're from the South of here? I never knew that some kingdoms have strong swimmers visiting."

Byleth sighed in relief at his sentence, "Oh you were reading a book before. What was it about?" Dimitri quickly got his book, "It's a language book. It's about sign language. Some people can't hear or speak so they use sign language to communicate." Byleth suggested, "Maybe we can learn together." "Sounds like a plan."  
  
Byleth and Dimitri spent hours talking to each other with their hands and reading from the book looking at what signs they could shape their hands into. "What does this sign mean?" "It means I'm sorry." "What about this one?" "It means thank you." "What about this one?" "This one is about... TIME!" He gasped as he saw the sun setting in a sky that was bright orange and crimson. "I'm sorry Byleth the sun is setting I've got to go back home." He closed his book and began running deeper into the land, "I hope to see you again!" He shouted, "I promise you will see me, Dimitri!"

Once he was out of sight Byleth dove back into the sea and headed home before Jeralt wondered where she was. "I can't believe I met a real human today, he wasn't dangerous and he had the most remarkable blue eyes. I can tell that he and I will become wonderful friends."  
  
Far away in a dark cavern a bubbling cauldron, a deep and sultry voice chuckled. "Hmm hmm hmm. Yes, swim home little mermaid, wouldn't want your daddy to know where you've been especially with a human prince. I can't do anything with you right now. But maybe those urges you have will be key to the undoing of little prince Dimitri and his kingdom."


	2. Schools, Sothis, Surfaces.

**Summary for the Chapter:**

> After a long discussion with Queen Reha about Byleth's safety, she is accepted into Ocean's academy, an exclusive school that Jeralt went to in his youth. But as she attends she hears the mysterious voice that guides her to follow her passions and still visits the surface to see the little prince, Dimitri.

Byleth quietly swam into her room, unnoticed by anyone. Meanwhile, in a separate room decorated with seaweed and corals, Jeralt and Queen Rhea chatted away, "You want her to enroll for her safety?" "Yeah, I'm a knight but she's too young to be at my side for work. She's only inching near her tenth year, I want to wait until she's stronger and at least 17 before she can come with me again. She was by my side for so many years, but I need to get more work done so she can live a better life. And the work is too dangerous for a kid her age to be around." Rhea bit her lip, "Are you sure you truly want her to study at Ocean's Academy?" She asked, " Jeralt firmly answered, "It's where I learned to become a knight myself and it will keep her safe."   
  
Seteth entered, "Excuse me but I agree with Jeralt, it will also protect her from dangerous things like humans." Rhea's eyes popped at the word humans, "You are correct Seteth!" Jeralt agreed, "Humans are very dangerous to us merfolk. It will be the only way to protect her from them. I couldn't protect my wife from them, but I can protect her now." Rhea then grabbed a piece of paper and scribbled on it before stamping a gold wax seal, "Sir Jeralt Eisener, your daughter will be enrolled at Ocean's Academy effective immediately." He bowed, "Thank you, Your Majesty."

Safely in a giant purple clamshell bed, Byleth tried practicing the signs she could recall from Dimitri. "I know I can get the hang of this eventually." But pretty soon there was a _KNOCK KNOCK KNOCK_ on her door. "Come in!" And Jeralt pushed the door open. "Byleth, how are you?" "I'm doing fine father. Is there any news?" She asked. "Yes, starting tomorrow, you'll be living and learning at Ocean's Academy." He declared.

"Oceans? Isn't that your school father?" Jeralt nodded. "Queen Rhea and I spoke about this, we know that your tenth birthday is coming soon. And I've been assigned more tasks as a knight. Sure I have taught you a lot over the years, but you need a good education, and I also need you to be safe because these new assignments are too dangerous for a kid your age. So what do you say?"  
  
Byleth tried to reason, "But father, we've been on missions since I could swim on my own. What makes these new missions so dangerous compared to the others?" Jeralt breathed deeply, "These are missions that involve dangerous merpeople, sea monsters, and sharks, possibly even humans." Byleth rolled her eyes at that last comment, "Humans again? But I don't think they can be so bad."   
  
"Byleth! I have told you several times, they were responsible for killing your mother. I have no problem if you find stuff from a sunken ship or a lost tool or something, but don't go near the surface. I only want you to be safe." He scolded. Then he calmed down and stated, " Look Byleth I know you're not like other mermaids. So I promise you that you can come on adventures with me when you're at least 17. Right now your education and safety are what matters. Agreed?"

Byleth held out her hand. To her, the possibility of vast adventures with her father was better than just being stuck in one area of the oceans all day. "Okay, father." And she shook his hand.

**THE NEXT DAY**

Byleth arrived at Ocean's academy's front door which looked like a castle and church building mashed into one. it was structured with marble stones, corals, seaweed, and shells that looked as if it popped out of a fairy tale. She then made her way to her homeroom and saw that there were at least a dozen or so students just around her age all with different colored tails and hair. _"I can't believe there is a school like this."_ Throughout the entire day, Byleth quietly studied and didn't really talk to anyone else. Yet one room caught her eye immediately.

"A Library. I wonder what kind of books they have in here?" Byleth then saw wall to wall books being stacked up and down every row and she swam to almost every nook and cranny. And one book's title in a far off corner isolated from other merpeople in the area drew her in like a magnet. "Humanology: The study of humans? That's interesting." She opened the book to see pictures of everyday human objects and their purposes. From telescopes to jewelry to corks and clothes. "I wonder if they have any more books like this."  
  
Suddenly, a small voice uttered, "Interested in humans aren't we little one?" Byleth flinched, "Wha?" She soon saw a young girl with long thick forest green hair and a long navy dress with golden trims floating in front of her. "W- Who are you?" Byleth asked, "I am known as Sothis young mermaid, I am also known as 'The Beginning'. I have seen for some time that you have a fascination with humans." "Y-You could say that."

Byleth then saw the bottom of her dress hemline, she didn't have a mermaid's tail instead she saw legs just like Dimitri's except longer and bare. "Are you a human? How are you breathing underwater?" She asked. "I am not a human nor a mermaid I am what people have referred to as a spirit or goddess. I am here to guide you, little mermaid. And I know you've talked to a human boy yesterday?" Byleth shrunk at that question and whispered, "How did you know? And yes, I did but he wasn't harmful. He was nice and friendly." "Rebellious aren't we?" Sothis quipped. "Well if you really do trust him, go see him again." Byleth gulped, "G-Go see him again?" Sothis inquired"Does he know you're really a mermaid?" Byleth shook her head. "Then do what you did last time and go see him again."

A giant grin was plastered on to her face as Sothis said what she said. But then she stopped in her tracks, "Hold on..." And skimmed the humanology book, "Clothes, He didn't know I was a mermaid because of the rocks. But if I want to get closer, I better take precautions." So Byleth snuck out of school and searched the ruins of a sunken ship that was nearby and found an enormous ragged ivory sail with some holes the size of Byleth's head in it, yet it was still sturdy enough to stay together along with some rope attached that was still stable. "This should work for my body, it's long enough to cover my tail."   
  
After several minutes of wrapping her body in the rope and cloth, she successfully covered her body and breached for the surface again out of the sight of anyone in the ocean. Just like yesterday, she saw Dimitri in the same spot reading the same book. And instantly swam over still hiding her lower body as much as possible from Dimitri. Once she got close enough to him she shouted, "DIMITRI!" And waved at him. "Byleth!" 

Byleth swam towards the shore with her dress still covering her tail and Dimitri went as fast as his legs would carry him. "It's good to see you again Dimitri." She greeted. "Likewise. So how about we continue to learn sign language?" He suggested, and she agreed. While talking they spent most of their time together making new signs and old signs with their hands, sometimes even signing a sentence or two. But soon Dimitri looked at the sun, "Oh dear, I need to go soon." And he ran away from the shore waving at her, "I hope to see you again tomorrow Byleth!" "Me too Dimitri!"

And once he was out of sight, she dived back into the sea and got out of her dress. "I better bring this with me, it worked today and I know it's going to work tomorrow as well. I know that humans can't be bad." And she swam towards Oceans before Jeralt arrived to meet her. "Hey kid, how was your first day of school?" Jeralt asked. "It was great, father." Byleth answered. But he noticed the cloth under her arm. "What's that?" Byleth's spine shook at the question and she bit her lip, "J-Just something I found I thought I could use it for crafting something yeah." "Okay, that's nice. Let's go home for today." Byleth felt as if a rock had just been lifted off of her back. _"Oh good, he had no idea."_

After that day, it became almost routine for Byleth to go to school, do school work, study humans, meet Dimitri, learn sign language, and hide it all. And she was sure this was something that could last forever.


	3. The Parting, Return and the Rescue.

**Summary for the Chapter:**

> As ten years passed, Byleth kept on collecting human objects and kept on seeing Dimitri to the point where they have become fluent in sign language. However, on the day of Byleth's graduation from Ocean's Academy, she visits Dimitri to find out news that drove them apart. But by the time he's back, Byleth has to do something that Merpeople are to never do.

**TEN YEARS LATER**

At Ocean's Academy, a young mermaid was in her classes with teal hair a slender and mature body, and a deep violet tail whose scales shone very bright in the sun. "Good morning Byleth!" Waved a mermaid with pink hair in pigtails. "Good morning Hilda." "The pleasant morning to you Byleth" Greeted a magenta haired mermaid with tan skin. "Good Morning Petra." "A lovely morning to you lady Byleth." Called a purple-haired merman. "Good morning Lorenz." Byleth swam her way to class as usual and floated in her section as a merman with a long brown robe, greying hair, and a monocle floated to the front.

"Good morning class." "Good morning professor Hanneman" The students uttered. "I see everyone is here today, and I am happy to announce graduation is happening soon. Allow me to announce this year's graduating students." He took out a scroll and began to read, "Our graduates for this year are, Hilda Valentine Goneril, Dorothea Arnault, Ferdinand Von Aiger, Yuri Leclerc..." He kept going down the list and eventually said, "and Byleth Eisener. Congratulations to everyone tomorrow. Now our lecture will begin." After the lecture was over, the graduating students all hovered around each other, "Finally graduation is upon us. After graduation, I'll just go back home and see what I can do when I can create fashionable accessories for everyone." "I'll find my way back to being a songstress siren for the Opera company." Ferdinand then turned to Byleth, "What about you Byleth? What are your plans?" 

Byleth bit her lip but then answered, "Do some knight work with my father and read books about humans." Everyone's eyes popped and their jaws dropped when they heard the word, humans. "Humans? Byleth why would you be interested in humans?" "Didn't Jeralt ever teach you that humans are dangerous when you were a kid?" "That's rule number one of the merpeople, Byleth!" "And we're never supposed to talk to them! It's forbidden!" 

"Then why are there books about humans?" She asked everyone. "We don't have to be so closed-minded about things we don't know." Dorthea rolled her eyes at her, "Byleth I thought Ferdinand was impossible, but you are beyond that. Even an idiot like Ferdie knows that we shouldn't do anything involving humans." Ferdinand nodded, "Yep! Wait! HEY!" All Byleth could do was swim away to her secluded spot in the library.

On cue, Sothis appeared in front of her "So you're being mocked for your dreams?" Byleth nodded. "I see it's difficult when merpeople have been taught to hate humans." But then she remembered all of her times with Dimitri, he never hurt her or even laid a finger on her, he was her only true friend. It was thanks to him that she had a better understanding of humans, and declared to Sothis, "After graduation, I think I'll go see him again." 

At the graduation ceremony, each merperson was lined up like soldiers. One after the other in a giant hall where it was decorated with colorful corals, pearls, and seaweed. It was like an ancient temple used by humans. Seteth got the scroll and spoke on the podium, "Good Afternoon students. I headmaster Seteth, am pleased to honor this year's graduating class of Ocean's Academy. This year's class will go on to do great things for the merfolk of the seas far and wide. Many will inherit their noble status, others will become knights, and others will choose their own path. So I present the class of 1180 with their diplomas."

Seteth then called each graduating student up one by one in alphabetical order. Pretty soon Byleth's name was called and she picked up a scroll and headed back to her place until the ceremony was over. The instant it was over, she swam as fast as she could to the dark area covered in stones, there she spotted the giant stone from all of those years ago and moved it before going inside to a grotto now filled with as many objects as far as the eyes could see. After putting down the scroll, she found her disguise dress that was now all covered in different patches but looked more and more like a real human dress than it did in her childhood. "I'm so glad I adjusted this."

Once she put it on, Byleth swam out of the grotto and to the surface without a single soul seeing her. The minute her head breached the water, she looked at the shore to see a figure moving on it. And she went back under the clear waves to paddle towards the shore as soon as she was close enough, she hopped on the rock again and saw Dimitri now with well kept blonde hair armored boots and wrists, a black outfit decorated with gold and silver embellishments and a blue cape. "Dimitri!" She waved, "Byleth!" As he came closer to her, she focused solely on his sapphire eyes that haven't changed since they were children. "I'm so glad to see you again Dimitri." Then she noticed his new clothes, "But I haven't seen that outfit on you before. What's the occasion?" 

He took a deep breath and sorrowfully answered, "Byleth, I forgot to tell you. It's a school uniform. I'm being sent off to Officer's Academy for studies. And I won't be back for five years." Byleth nearly choked. "W-Won't be back for five years? I thought you were done with school." "Byleth, I'm seventeen, and you're twenty. I need to go to this school so I can return as a proper king someday." Byleth's head started to droop but then Dimitri held out his pinky. 

"Byleth, I promise I'll return and I won't forget you." And Byleth wrapped her Pinky around his own. "Also, before you go I want you to have this!" Dimitri pulled out a sheathed dagger with a handle that was wrapped in the finest blue leather and the size of his head. "A dagger?" "Listen to me Byleth, no matter how hard things get for you while I'm gone, cut a path for the future you wish for no matter what." 

"Thank you Dimitri, I'll treasure it forever. Along with the sign language book you gave me last year. We have taught each other very well. And I will never forget your eyes. They're that same color I've known ever since you were a child." Dimitri soon traveled his way back into the land while waving goodbye and the mermaid swam out of sight still carrying the dagger the minute he couldn't see her.

Back under the sea, Byleth swam into the dark depths of her grotto and stored the dagger on an empty spot that stood in front of the entrance next to a book titled 'Sign language'. "Perfect, my two most treasured items. I know I'll see him again someday." Out of nowhere, Sothis quipped, "I see you're interested in this human boy aren't you?" Byleth responded, "He's not a boy anymore he's a young man and he has the most distinctive blue eyes." Byleth sighed and she smiled upon thinking of his eyes. "Wait a minute, if I didn't know any better you're falling in love with him aren't you?" Sothis analyzed.

"What, NO! That's impossible. He's a human a-and I'm a mermaid." She blurted. "You may say that now Byleth, but you can't deny your feelings, I know what falling in love looks like. But I won't try to change your mind." "Nevermind that, I'll just have to keep learning sign language and wait for five years. He promised me he'd come back so I'll be prepared for him. In fact, one day I will be beyond prepared for him because I would give anything to actually be human."

Meanwhile far out in the distance, a crystal ball showed the image of the young mermaid to a sultry, mature, and curvaceous woman with thick long flowing strawberry blonde hair and black octopus' tentacles for a tail. "Ah yes, the little mermaid is clearly falling in love with a human and actually wants to be a human. But of course not just any human, Prince Dimitri. Oh, how Reha and her father will writhe at that." She cackled, "But once she's in my clutches, Dimitri, the entire Kingdom of Fargues, and the Oceans will pay for what they did to me. Here I am banished, isolated, without any ways to take vengeance until now. But it looks like I'll wait until the princeling returns."

**FIVE YEARS LATER**

Throughout those five years away from Dimitri, Byleth kept on fighting at her father's side on missions and secretly kept finding human objects for her massive collection in her grotto and kept reading that sign language book Dimitri had given her. But one day when Jeralt had the day off, Byleth freely went to the ruins of several sunken ships, an area that was dark, green with very little light shining through, like a graveyard. Yet one object stood out amongst the algae-covered ships, a stone figure that looked exactly like Dimitri. "Oh, Dimitri, this even has his eyes. It must be from the last time I met him. There's no doubt he's changed over the last 5 years. I wonder what he looks like now." 

She swam out of the ruins and sighed as she looked up at the dark sky and the moonlight reflecting off of the water's clear surface. "But it looks like I'll have to wait until tomorrow." Before she could swim back home, a giant shadow floated over her head covering every coral and shell and stone in darkness until it passed over. Byleth instantly looked up and began following it. "What's this?"

She breached the surface and saw exploding lights in the stary sky all different colors and far as any eye could imagine. Byleth then swam closer and closer to the giant wooden floating object only to see that is was a boat as Dimitri described to her in their childhood years. It was carved to perfection with detailed craftsmanship, the wood was strong enough to hold several large animals and still float, and on the boat were humans drinking and eating and dancing just as she was told. _"Amazing, I've never seen so many humans at the same time. It must be very fun to be one."_

"So you've now become closer to several humans, my child. I'm glad you're living out your desires to see them more often." But Byleth could only pay attention to the humans on the ship. Seconds later, a towering man with dark skin and silver hair rang a bell the size of his head, _DONG! DONG! DONG!_ "Good evening everyone, I am happy to announce that we will be arriving at shore soon. We have returned from both our education and war. So I present to everyone the future king of Faerghus, Prince Dimitri Alexandre Blaiddyd." And Dimitri stepped out of his quarters looking completely different from five years ago. His stature was taller, his golden hair now neck length, his outfit now black armor with only a blue scar on his chest, and his cape was now floor-length and trimmed with an animal pelt on his shoulders.

"Thank you Dedue. Good evening everyone. I am glad we are all here to celebrate my return to the Holy Kingdom of Faerghus. Within two months I shall take my rightful place as king." He announced. "LONG LIVE THE KING!" Everyone shouted. But then a bright oranged haired man stepped out of line and stated, "And after our return, we shall also seek eligible maidens to become his queen." He was then slapped by a navy haired man with a sword at his side. "Sylvain you dolt. What makes you think the Boar prince is so concerned about getting married?" A slender young woman with short blonde hair soon followed, "Felix is right, not to mention you were the one that set up those failed engagements for him when we were on our way home, and you wound up hitting on them or making terrible arrangements in the end." Sylvain bit his lip, "A-Are you sure you remember correctly Ingrid?"

Ingrid rolled her eyes, "Oh if I'm not correct then why did we all have to write a 3-page long apology to the exalt of Yilisse when you set up an engagement with his daughter and his Highness despite the fact that she WAS ALREADY ENGAGED!?" Sylvain stammered, "Umm.. I-I!" "And the time you flirted with Princess Erika of Renais when his Highness was negotiating with her brother about marriage?" Shouted Felix. "He didn't like her!" A small and slender ginger-haired woman then uttered, "But I do remember her brother liked chasing you, Sylvain." "Annette!" Everyone at the table kept laughing. "Alright settle down everyone that's a matter between his Highness and me." Stated Dedue.

As Dedue met with Dimitri he insisted, "Your Highness, while they were mocking Sylvain, they are right. Everyone in the kingdom is waiting for you to be engaged or married by the coronation. To settle down and have an heir to the throne." Dimitri nodded, "I am aware Dedue, but I want to wait for the right girl. I remember someone from my childhood but I don't know if she'll come back to me. But we did make a promise." Byleth's face turned into a beet, _"He's talking about me."_

"Your Highness, I never saw this girl." "Dedue, I know in my heart I will find the right one and it will just hit me like lightning." But the minute he said lightning the sky sounded, _CRASH! BOOM!_ Byleth jumped off of the boat side and dived underneath the violent waves that slammed the wood of the boat. "STORM COMING!" "EVERYONE UNDER THE DECK!" But lighting struck into the sails and the boat was instantly on fire. "TO THE LIFE BOATS!" Byleth peaked up to see the fire spreading fast as if the boat was made of dried grass. Dimitri was about to get into the lifeboat but the flames found their way to a barrel of gunpowder _BOOM!_ Went the ship, wood scattered everywhere and Dedue shouted "YOUR HIGHNESS! WHERE ARE YOU?" And everyone kept shouting Dimitri's name with no answer.

Byleth soon found his body drifting on a piece of wood that could barely hold him and he slipped off as his body fell helplessly into the sea. Byleth swam for him as fast as her fins could flip and found her arms under his armpits and began to drag him to the surface. Byleth then swam to the shore keeping his head above water. When she got to the beach with his unconscious body, Byleth put her ear to his chest. "Please Dimitri, don't die." But eventually saw his mouth open and his chest rose up and down. "Oh thank the Goddess, he's breathing." She moved his hair away from his face and looked at it, "He's so handsome."

Byleth started to vocalize, "Ahh ahh ahhhh. In time's flow... see the glow of flames ever burning bright... On the swift rivers drift, broken memories alight..." The sun peaked through the clouds and Dimitri's eyes began to open, he could only see a blurry image of her but he could still hear her voice. Once Byleth finished her song, she could hear footsteps and a voice, "Your Highness!" And she dove back into the water.

"Your highness, you're alive!" As Dimitri collected himself he recalled, "There was a girl who rescued me Dedue, and she sang with this beautiful voice. I feel like I heard this voice before." Dedue put Dimitri's limp arm around his shoulder and escorted him home, "I think you drank a bit too much seawater, Your Highness. You're safe now so that's all that matters." 

"You rescued him, knowing that he's a human?" Sothis inquired, "He would've died. Besides, I guess you were right, I saved him because I love him." Byleth answered. "Sothis, I don't know when or how, but I swear that one day I will be apart of the land."


	4. Shattering and Cornelia

**Summary for the Chapter:**

> After rescuing Dimitri and falling for him, Byleth starts to act differently around everyone who knew her and it doesn't take long for anyone to figure out that she's in love. However, when Flaynn starts following her, she discovers Byleth's secret and Jeralt and the Queen don't take well to it. Bitter at her sea life for shattering her dreams. She decided to make her dreams come true with one last resort, Cornelia the sea witch.

The very next day when Jeralt called for Byleth, she didn't come out of her room for hours. "Byleth, I need you to run some errands today! You've been in there all morning." Byleth came out with a flower in her hair and humming a small tune. "Oh sorry, father. What do you need?" Jeralt answered, "Just pick up everything on this list at the market okay kid?" Byleth wafted in the scent of the flower in her hair and sighed, "Yes father." She took the list with her and her bag while putting the same flower in Jeralt's hair. And she swam away as if she was floating on clouds still giggling to herself. "What's with that girl?"

Byleth gently floated to the market still humming that same tune and picking up another flower along the way. "This one reminds me so much of his eyes." By the time she got to the markets, the stands were all dotted wall to wall with merpeople shopping and browsing the various goods and foods. But rather than follow the list, Byleth went to a beauty stand that was set up with various lipsticks, beauty creams, eyeshadows, and glitters. "Welcome miss, I see you have an eye for cosmetics. May I help you?" Byleth looked at the deep red shade of lipstick and a scene played in her head where she was walking next to Dimitri's side on the beach with human legs and the shade coating her lips. His shining sapphire eyes looking into her violet ones uttering the phrase, "Byleth I love you. Please stay with me forever." He leaned in to kiss her but Byleth kept hearing a voice echo.

"Miss? Miss? MISS!" And then she came back to reality. "Oh, the red one please." After paying for it and putting it away in her bag Byleth continued to float in the market but kept giggling to herself along the way. Unbeknownst to her, familiar faces from her school days were at the same market. Each one of them has matured past their school years and was now working inheriting their lands or even starting their own businesses. "Is that Byleth?" Dorthea whispered to herself. Then she bumped into a pink-haired woman, "Oh, Hilda I didn't see you there." "It's no big deal, but what are you looking at?" Dorthea pointed at Byleth floating and giggling like a child while smelling the various flowers at the market stands.

"Oh I see, Jeralt is going to flip when he finds out!" Hilda grinned. "Jeralt is going to find out what?" Inquired an orange-haired mermaid with shoulder-length hair and muscular arms. "I can't believe you're this oblivious, Leonie. It's about Byleth." Leonie then saw the mermaid in question. "Oh, I see what you're talking about." Then an aqua haired muscular merman overheard. "WHAT TALKING ABOUT WHAT?" He shouted. "QUIET GASPAR!" Dorthea held his lips with her fingers, "Listen carefully." She then whispered into his ear but then he shouted, "BYLETH IS IN LOVE!?" 

Everyone at the marketplace heard that last sentence and the three mermaids glared daggers at him, "Way to go, Gaspar, your big mouth is sure to get to Jeralt and her majesty now." Dorthea remarked. "My big question is who the merman or mermaid is." Leonie pondered. Byleth left the market with her supplies in tow and everyone started gossiping and conversing, "The captain's daughter is in love?" "I wonder who it is?" "Who's the merman she's in love with?" "It could be another mermaid too." Hours passed and the word of Byleth's new love life spread like wildfire across all of the ocean. 

Back at the palace, the gatekeeper was approached by Seteth, "Good afternoon sir. No news to report today. But have you heard of the latest town gossip? They are all saying that Captain Jeralt's daughter is in love." Seteth shook and then rubbed his ears, "Sorry, could you say that again? Did I hear correctly from you that captain Jeralt's daughter is in love?" The gatekeeper simply nodded. "Brother? What is this news?" A young mermaid with thick aqua hair in loose curls approached him. "Oh, Flayn. Aren't you supposed to be taking care of the seahorses right now?" "I'm already done with that, brother. I couldn't help but overhear that Byleth is in love." The gatekeeper nodded again. "Yes, everyone in the market place saw it." 

Byleth swam to her quarters humming to herself still, once she dropped off supplies for Jeralt. She floated past the area where Flayn and Seteth were still floating but her giggling was in earshot of them. "Flayn, something seems suspicious about where she's going. Very few merfolk even go to that area, I request you to follow her, but be back soon." "Yes, Brother." As Byleth swam, Flayn quietly paddled after her. Past the coral reefs, into the thick kelp forests, and over the steaming vents where little light shone.

Byleth made her way into her grotto and quickly went inside. Unknowing to her, Flayn discreetly floated outside and listened to every word. "The people in the markets are right Dimitri, but I don't care anymore, I love you! I can't wait to be apart of your world out of the ocean and into your arms." _"Dimitri!? There are no known records of any merman named Dimitri!"_ "You've helped me learn sign language, and you were the only boy that didn't think I was weird. But after rescuing you, I know that you were more than just my friend. One day I know I'm going to be with you forever." The gears started to turn for Flayn, _"Years, rescue, no merman named Dimitri."_ Then it hit her like a fifty-pound mallet. _"She's talking about a human!"_ She mouthed and quickly swam back to the palace.

Back at the palace, Flayn got back to see that her brother was now with the queen and Jeralt. She announced very quickly. "Brother, Your Majesty, Captain! I-I found" She stopped to breathe out. "Child, please collect yourself, what is the news?" Questioned the queen. "Take it easy. We all know Byleth is in love so we know that's not news." When Flayn heard Byleth's name she shot up, "That's what I've been trying to tell you, it's about who Byleth is in love with. It's not a merman, nor mermaid or any type of merfolk. It's a human!" Everyone's hearts sank at that last word, "A what?" "HUMAN!" "Flayn what else do you have to tell us about this human?" Flayn made a follow me motion and everyone swam after her. "I'll tell you more along the way."

In Byleth's grotto, it was now decorated with human objects with every single rock filled with chests, tools, books, paintings, gadgets, and cloths. "All of these years yet it's not the real thing. But one day I will be part of that wonderful world with Dimitri at my side." She sighed. "Byleth!" She turned around to find the stern face of Jeralt looking at her like a predator ready to pounce. "F-father!" Rhea swam in and saw Byleth's entire collection of human objects surrounding her.

She growled at Byleth, "So, this is the secret you have kept from us, my child? We consider ourselves to be reasonable but is it true that you have been seeing this human for years and then saved him from drowning?" "Your Majesty! Please He didn't see my tail. And he could've died!" Seteth then yelled, "It doesn't matter! You know that contact between the human and merpeople world is forbidden! Everyone knows that. Even you!" "But..." Jeralt called out at a high volume, "I can't believe you lied to me all of those years! I have told you time and time again to stay away from the surface! Your mother was killed there! This boy would've killed you, yet you saved him!? Just one less human isn't going to make a difference!"

Everyone kept yelling and telling her that seeing Dimitri was wrong. She got her reason buried under everyone's remarks, it was like a stone after stone burying her body. But she cried out with all of the might in her voice, "NONE OF YOU KNOW HIM LIKE I DO! YOUR MAJESTY, FATHER I LOVE HIM!" Everyone went silent as those last three words were spoken. Rhea's jaw dropped and everyone's eyes popped, "No! It cannot be. He's a human you're a mermaid!" Byleth shook her head, "I don't care! I love him!" 

"Jeralt, keep the child away! I know what I need to do." Her hands started to glow bright red and then sparked a bright light. "Byleth my dear! If this is the only way I can get through to you, so be it!" Rhea then waved her hands and lighting came out of them destroying every bit of Byleth's collection. "YOUR MAJESTY STOP! PLEASE STOP!" Jeralt held her back as everything was turned to shards, splinters, and scraps. Then one last object was in her sight the sign language book. "YOUR MAJESTY NO!" But it was too late, the book exploded and every page turned to burnt scraps! Byleth was let go and scrambled to collect what remained of the book but started sobbing. Everyone left biting their lips as they heard Byleth's tears.

She cried with her destroyed collection for what seemed like hours. But then she saw a small object shining under the rubble and dug it up. "The dagger he gave me! It's still safe." She then saw a cloth that was still in a large piece. "And my dress, it's a little ratted up but I can still wear it." And she cuddled them both like a stuffed animal. "Dimitri told me that this dagger is meant to cut my own path and I will! There is one place I can go where my dream can be made possible! It's risky but I'll do it if I can see him again." Sothis then popped up and warned her, "Are you sure about this? Visiting the sea witch, Cornelia is incredibly risky. I have seen what she has done in her life and she's not safe in the long run."

Byleth ignored Sothis' plea and swam away from her now empty grotto with the dagger wrapped in what remained of her dress. Into much hotter steamier vents, deeper and darker trenches, and dead corals. She then arrived at a cave much bigger than her old grotto but twice as dark with glowing kelps everywhere as her only source of light. As she swam in she could see faces attached to what looked like wriggling green creatures moaning for their lives. "Hello? Cornelia?" Byleth called. Soon Cornelia arrived in Byleth's presence with her tentacles moving her around towards Byleth's position. "Ah come in my dear. I know very well what you've been through."

Byleth's heart beat faster and she bit her lip, "Y-you have?" She stuttered. "I have, I am the sea witch after all. I have seen all the lives of merfolk like yourself. And I understand you're in love with this prince." Cornelia then caught sight of the cloth, "Now what's in your hand?" Byleth unwrapped the dagger. "Ahh, I see a dagger from the prince's land. The same one he gave you five years ago. And isn't this the dress you used to hide your tail?" Byleth unfolded it to reveal that the lower skirt half was shredded too short to hide her tail and the bodice's sleeves were singed clean off. "Well, what's left of it."

Cornelia smirked as she scanned through her collection of glass bottles and potions. "Well my dear, I do have a solution to your problem." Her tentacles touched Byleth's chin and raised it to her face, "I have the ability to make you a human for your prince." "C-can you really do that?" Cornelia smiled smugly, "Why yes my dear, I have solved so many problems in the past for so many merfolk like yourself. You had nobody else to turn to because you were an outcast, a miscreant, an amateur humanologist. So I know exactly what to do. But you need to listen carefully."

One of her tentacles brought in Byleth closer to her. "Now I am going to make you a potion that will turn you into a human for two weeks!" She held up two fingers. "Remember that well, two weeks." And brought her over to a glowing mushroom-shaped cauldron that could open and close on her command. "Now pay attention." The stone opened up and began to glow like the sun. "Before the sun sets on the fourteenth day, you need to have the prince kiss you." And the cauldron showed a glowing red heart. "However, it's not just a simple kiss, this is the kiss of true love. And if he does declare his love to you and kisses you before the last sunset, you will remain a human forever!" And she was presented with a glowing image of her silhouette running freely as a human. "But if he doesn't you become a mermaid again." The image changed to her mermaid form. "And you become part of my collection!" 

Cornelia's tentacle tips touched Byleth's shoulders like hands. "So do we have a deal my dear?" Byleth froze but heard Sothis' voice say, _"If you become a human, you'll never see your family and friends again. And if you fail you'll be in her possession forever. Is your life truly worth the risk to become a human?"_ Byleth bit her lip, " This is not an easy choice. Right now I feel like I don't belong here, I'll do it!"

"Very well! Now we're not going to become human for free. In exchange for this potion, you will give up two things. The first, your voice." Byleth touched her neck, "My voice?" "Correct, but since you know sign language as well, the second item will be Dimitri's memories of you. If he saw you and recognized you it would be way too easy. So you'll have to start your relationship over from scratch. You're pretty enough my dear, so once again?" Cornelia rolled out a scroll, "Do we still have a deal?" Byleth nodded. "Yes." And she signed the bottom of the scroll.

Cornelia then threw glass bottles filled with mysterious goop right into the cauldron one by one. It began to smoke different colors with every bottle. "Now I just need one more ingredient. Put on your tattered dress, and hand me your dagger for a minute." Byleth put on the dress and handed the dagger to the witch, "But what do you need it for?" She then grabbed Byleth's hand, "The last part of the potion requires a sample of your own blood but the skin has to be cut by a human object." She quickly nicked Byleth's knuckle and small droplets of blood began to flow out and were sucked into the cauldron. "Now we begin."

Cornelia waved her hands and chanted "Elanegs meto voxius. Elanegs meto voxius." The cauldron began to bubble and smoke and flashed a slimy seafoam around the room turning the water around it into a whirlpool of bubbles rapidly surrounding Byleth's tail. "Now open your mouth!" And Byleth opened her mouth as wide as she could. She then felt something in her throat as if her neck was on fire but then her neck began to glow and it slowly moved out of her mouth and into a conch necklace on Cornelia's neck. The bubbles on her tail soon encased her entire body as Cornelia cackled. Byleth's body was carried towards the surface and her tail sparked and flashed along the way. It was like being struck with a thoron spell with every flash her tail couldn't even move.

Her body drifted closer and closer to the surface with every flash and closer to the shore. The strikes on her tail could even be felt on the rest of her body and turned her dark ocean green hair and violet eyes into a light seafoam color. But the moment she was inches away from the surface, _RIIIIP_ and her tail was no more and she had only her torn dress covering her. Upon breaching she paddled as much as she could to the shore where she collapsed on the warm white sand trying to softly inhale and exhale with her new lungs. 

A tall shadow walked by her unconscious body and instantly ran towards her. "Miss are you okay?" It asked. "Oh dear, she's breathing but she's not responding. Dedue, get Mercedes! This poor girl was shipwrecked!" "Yes your highness."


	5. The Human World

**Summary for the Chapter:**

> Byleth now lives her dream of being a human. She could do so many things she couldn't do before when she was a mermaid. She could walk, run, and dance, but just as Cornelia stated she couldn't speak and Dimitri's childhood memories of her were wiped clean. But she could still speak to him with the sign language she learned over the years. With every effort, Byleth tries to fit into the human world and tries to get Dimitri to fall for her. But learns more about him on the way including what happened to him since those five years.

When Byleth's eyes reopened, she was no longer on the white sands of the beach but rather a velvet lined carriage and Dimitri sitting across with Dedue next to him. Just seeing his face made her smile. "You're awake now. I'm glad I found you out there on the beach, Miss, I am Prince Dimitri Alexandre Blaiddyd, what is your name?"   
  
Byleth tried to speak but nothing came out of her mouth. "Your highness, she seems to be a mute." Observed Dedue. Then a spark went off in her mind and she began to sign out letters with her hands.   
  
_"My name is Byleth."_

"Wait a minute, you speak sign language?"   
  
Byleth nodded rapidly.   
  
"That's great to know. I learned sign language when I was a boy from a book."   
  
The carriage soon stopped and Dimitri and Dedue made their way out. But Byleth stayed behind gazing at her new set of legs. _"Legs human legs. This is the best day of my life! I'm a human!"_ All she could do was smile and touch her new legs.   
  
"Byleth?" Called Dimitri. She tried to step down from the carriage but almost fell flat on her face before Dimitri caught her. "Careful, that wreck must have done a number on you. Since you have nowhere to go, you're my honored guest. We'll get you freshened up." Byleth continued to trip and fall and stumble as Dimitri walked her to a giant marble palace decorated with intricate golds, ivy, flowers, and granite that could almost rival queen Rhea's castle.

Once inside, Byleth was immediately put into a bathtub where a gentle speaking short haired blonde girl was in her presence instead of Byleth instead of her prince. "Oh dear, washed up from a shipwreck. It's best to get you cleaned up as soon as we can. I'm Mercedes and I'm the castle's head baker and nurse. Now please hand me your wrecked dress. I'll give you a fresh supply of clothes." Byleth did as she was ordered and Mercedes gently turned on the water which splashed on her legs and was as warm as a hot spring. Byleth touched the flowing water as it came from the metal pipe. "It must have been a while since you've had a bath. I'll get some oils and soaps for you." Mercedes soon came back with bottles and splashed the liquids into the running water that made the soap bubble all over Byleth's body. As some floated in the air, Byleth tried to hold them but they popped as soon as she touched them. _"So this is what bubbles are like on the land?"_

Mercedes began to exit the room, "Now take your time. I'll be back with some fresh clothes."

Meanwhile, in another room, Dimitri sat at an ebony grand piano playing a small melody. "Your highness." Dedue addressed. And Dimitri stopped playing. "Are you playing that song again your highness? We have looked for days trying to find this mysterious maiden who saved you and not one person has shown up. Need I remind you that the coronation date has been set to three weeks from now and the kingdom is expecting you to get engaged soon."   
  
Dimitri interrupted, "Dedue, I am certain that the girl who rescued me was real." 

"Oh come on your highness, you've never been able to find the right girl. You've always had trouble with girls since we were kids." Quipped Sylvain as he walked in.  
  
As if on cue, Ingrid followed, "Oh but you're one to talk Sylvain! Are we forgetting your skirt-chasing? Or how about the time you hit on my granny when you were eight!? MY GRANNY!" Dimitri and Dedue started snickering.   
  
"I WAS A STUPID KID!"   
  
Ingrid continued, "Or how about the time when you were ten and made eyes at a scarecrow? HUH!?"   
  
"It was an accident! I thought it was a girl from behind!" Dedue and Dimitri began to giggle even louder.   
  
"And who's job was it to settle conflicts with when your engagement plans for his highness failed because you flirted with his potential suitors? Hmm? ALL ME!"

Sylvain shouted, "ALL RIGHT ENOUGH ALREADY! I'll stay out of his highnesses love life. But I'm just saying he's had trouble with girls for most of his life, but now he's bent on marrying some mystery woman that we don't even know! I mean Dedue could be right, for all we know she might not even exist!"   
  
Dimitri shot up, "Sylvain! I know she was real! I am alive because of her and she will be my bride."

"Your highness, Lady Byleth is ready," Mercedes announced her presence as Byleth slowly walked in, still unsteady in her new form and even more so in her new attire. She was wearing a set of jet black armor that did fit her body, but to her, it felt clunky and uneven. She was given a linen coat that appeared as more of a cape, something Mercedes referred to as stockings made of lace and heeled boots. The item of clothing that was most comfortable for her was the mid-drift bodice and shorts. Mercedes continued speaking and Byleth slowly focused on one step after the other in her new shoes. "I know it's not much your highness, but it was the only women's outfit we had left." Dimitri scanned Byleth's entire figure and his heart skipped a beat at the sight of his guest.

"Y-you look great," Dimitri stammered.

_"Thank you,"_ Byleth signed.

Dimitri soon took her small hand in his much larger one and guided her around as she constantly stumbled and struggled to walk in her new shoes. To Byelth, walking in human legs without her shoes felt like trying to carry her upper body on what humans called wheels as she constantly slipped and slid while walking for her first time. But with her shoes on, it was like trying to navigate through a path of broken glass. Just one wrong step and she would wince in pain or hold on to Dimitri's wrist for dear life.  
  
"I see the wreck did a number on your legs. But I'm glad I could show you around my castle. We'll be having dinner in a little bit, I would love for you to eat a nice meal today." Byleth nodded. 

They approached a room with a table that was long enough to be a boat on its own surrounded by velvet decorated chairs. "Ah speak of the devil. You can sit next to me." And Byleth gently sat in her chair right next to him. "We have many things that I hope you'll love. We have pheasant, sweet buns, and salads. I would've gotten the chef to make some fish but after being at sea for weeks I'm tired of it." 

_"So humans don't just eat fish. And I've heard of this food before, it's called dinner and desserts."_ She thought.   
  
"Still, where are my manners? Tell me a little about yourself Byleth. I should at least get to know a guest."

Byleth looked directly at Dimitri signing, _"Well I really enjoy learning sign language and reading. But I also love to explore new areas. Don't you think it can get a little boring being cooped up in the same place all the time?"_

"Amazing, you're very outgoing and open-minded. I like that in a person. But to tell you the truth after traveling for months on a boat. I'm just glad to be back home. Especially after a war."

Byleth's eyes popped. _"A war? Why did it have to happen? No, tell me what happened please."_ Dimitri breathed in and bit his lip.  
  
"Well, it all started when I left for school five years ago. During my time at the Officer's Academy, I was living a pretty average student life even as a royal. But the academy is run by the Church of Serios, so there was always the occasional conflicts that happened." He took a deep breath again, "But then came that terrible day when I found out that my former stepsister, Edelgard was behind so many unfortunate events. Then she seized the throne from her father back in the Adrestian Empire and declared war against the Church of Serios. During those five years, I was accused of a crime I didn't commit and I escaped execution at the last minute. And I thought my closest friend, Dedue took my place. Since then I was filled with only revenge, thoughts of murder, and anger. And I never thought I would be able to talk to anyone again until my comrades and army were properly guided under the leadership of my professor, Bereto. He was a kind and wise man, and thanks to him, we were victorious over the Empire. While I was with him, he was very curious about our lives outside of school, he was very helpful, smart, creative, knew a lot about fish, and he was so nice to talk to. To be honest, he did remind me of someone who I can't really remember right now."  
  
Her heart popped. _"He's talking about me!"_

" _Did you meet this person he reminds you of when you were a child?"_ She quickly signed to him as her heart swelled. _  
  
_Dimitri shook his head, " I can't remember too much, but you must be starving right now as I go on. So let's have our dinner and tomorrow I can take you around my Kingdom since you've never been here before. Do you consent?" Byleth quickly signed, "Yes I would love to."  
  
Later in the evening, Byleth changed out of her clothes and looked at the clothes Mercedes left behind in her room. She found a flowy light dress that was called a nightgown it was the same color as her old tail. And her bed was similar to what she slept in under the sea, but it felt softer to her as she pulled back the strange new covers that she sank into as they wrapped her in their warm embrace. To her this material was something she only read about in books, it was called silk. As she was about to rest her eyes, Sothis began to speak again,   
  
_"So you finally live amongst him."  
  
_ Byleth's eyes shot up wide open. _"You seem happier as a human. But you have to remember, you sacrificed your life as a mermaid to be with him and starting right now we have thirteen days for him to fall in love with you. And you will belong to Cornelia if you fail. So don't waste any time starting tomorrow morning."_

_"I won't I understand that this was an incredibly risky thing to do Sothis but father and the others just didn't understand me. They were so closed-minded for my interest in humans, and my love for Dimitri. So I am not going to let this chance go to waste, I promise that I won't fail."_ She signed. And then she slowly drifted off to sleep.


End file.
